Picture and Explanation of How Your Body and Baby are Growing and Developing at 20 Weeks Pregnant

By
the 20th week of pregnancy, the uterus can be felt at the level of your
bellybutton (umbilicus). It began rising into the abdominal cavity soon
after the beginning of the 12th week, when the baby and uterus were
outgrowing the pelvic cavity as a comfortable abiding place. As a
result, the pelvic colon and small intestines are crowded upward and
backward. The ascending and descending colon, because of their close
attachments to the back of the abdominal wall, maintain their usual
positions.

The enlargement of the uterus during this week is greatest at the site
of the placental attachment (usually on the front or back wall), so the
uterus has an asymmetrical bulge. The wall of the uterus, which
lengthens and thickens early in pregnancy, stretches as the fetus
grows, and becomes thinner now, only 3 to 5 millimeters thick. The
bladder ascends but not as much as the uterus, which straightens as it
ascends.

Your ascending uterus rests against the lower portion of the front of
the abdominal wall, causing it to bulge forward noticeably by your 20th
week. The amount of the bulge is influenced by the tone of the
abdominal muscles. If they are firm, the uterus may be pressed against
the spinal column, and there will be no noticeable bulge; if they are
weak, the pressure of the uterus against the interior wall produces a
sizeable bulge.

The position of the uterus during this week explains why you may
feel more comfortable at this stage than earlier in your pregnancy.
Pressure within the pelvic cavity, which during the earlier weeks may
cause weariness and frequent urination, is relieved when the uterus
ascends into the abdominal cavity.

Childbirth Connection is a national not-for-profit organization founded in 1918 as Maternity Center Association. Our mission is to improve the quality of maternity care through research, education, advocacy and policy. Childbirth Connection promotes safe, effective and satisfying evidence-based maternity care and is a voice for the needs and interests of childbearing families.